After upgrading to 3.1 The CUSTOM FIELD and other stuff where gone totally for my users EDITOR and AUTHOR. but viewing it as administrator seems to have no problem but for the autors and editors users in the site all these features are gone in creating new posts.
Did you look at “Screen Options” on the top right when you are editing or creating a Post or Page? 3.1 hides some screen options by default. Just turn on the ones you want.
More info here: http://ottopress.com/2011/wp-quickie-metaboxes/